ABSTRACT Over 1 million people in the United States are living with multiple sclerosis (MS), and the majority of people with MS will experience severe, debilitating fatigue at some point. However, a psychometrically sound, publicly available measure of fatigue optimized for persons with MS has not been recognized by FDA as fit-for-purpose for use in drug development. We propose the preparation of a Qualification Plan to support the qualification of the PROMIS-FatigueMS as a patient-reported outcome measure of fatigue in individuals diagnosed with all forms of MS. A measure of fatigue, along with a measure of physical function, was accepted into the Center for Drug Evaluation and Research's (CDER's) Clinical Outcome Assessment (COA) Qualification Program under DDT #000069 on June 21, 2017. The PRO Consortium's MS Working Group has selected the PROMIS-FatigueMS as the fatigue measure for qualification as it has been optimized for use in persons with MS. As requested by FDA in the Letter of Intent response, an Initial Briefing Package is currently in preparation that documents the development of and content validity evidence supporting the PROMIS-FatigueMS. After the Initial Briefing Package is submitted to FDA later this year, the next step in the qualification process will be to submit a Qualification Plan to FDA to address the MS Working Group's research plan for obtaining the quantitative evidence necessary to support qualification of the measure for use in MS drug development. Our approach includes two aims. For Aim 1, we will develop the final protocols and statistical analysis plans for existing cross-sectional and longitudinal datasets that include the PROMIS- FatigueMS to examine its validity, reliability, and responsiveness as an outcome measure in individuals with all forms of MS. These protocols and analysis plans will provide the foundation for Aim 2, in which we will finalize and submit a Qualification Plan for the PROMIS-FatigueMS using the CDER COA Qualification Plan content outline. The long-term result of this project will be a publicly available and accessible PRO measure for assessing fatigue in MS clinical trials for all forms of MS. As such, qualifying the PROMIS-FatigueMS will fill a critical gap in the measurement of fatigue in MS treatment trials.